This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Using fluorescent probes is an important methodology for in vivo molecular imaging, particularly to study small animal cancer models. Nonetheless the lack of tomographical imaging capability is limiting fluorescence imaging primarily to topographical mapping of superficial tissue. Fluorescence diffuse optical tomography (F-DOT) is an emerging technology capable of resolving the distribution of fluorophore concentration in 3-D. However, the majority of existing techniques require fiber-optics to couple the light sources and detectors with the animal, which significantly restricts its applications and achievable resolution. We are implementing a non-contact F-DOT system that uses raster-scanning pulsed laser and time-gated intensified CCD (ICCD) camera with a rotational state for the animal to resolve 3-D fluorescence images. We will demonstrate our preliminary result from a phantom study using a scanning continuous-wave diode laser. Further study is under way in the directions of pulsed laser and time-gated acquisition;regularized image reconstruction techniques;and simultaneous multimodal imaging with our micro-CT system. We developed a fluorescence diffusion optical tomography (FDOT) method for in vivo imaging of small animals, which use x-ray micro-CT data as the structural a priori information to assist the FDOT reconstruction. This project involves hardware and methodology development, particularly the forward and inverse problem solvers for FDOT. The overall goal of the project is to increase the achievable resolution of FDOT for preclinical imaging applications.